The present invention relates to a machine for turning hosiery items such as stockings the right way out, with high operating reliability.
The term "stocking" is used herein, for conciseness of description, to refer to knit close-fitting coverings for the foot and leg, such as men's socks and women's stockings, as well as hosiery items which are subsequently interconnected for manufacturing women's tights.
It is known that the production process for manufacturing stockings comprises a step for the production of a tabular hosiery component that is open at its longitudinal ends and is then closed by sewing or linking at one of said ends that constitutes the toe of the stocking.
The operation for linking or sewing the toe of the stocking is performed while the stocking is inside out, and it is therefore necessary to turn the stocking the right way out again before packaging it.
Stockings are currently turned the right way out by using machines that are essentially composed of a structure that supports one or two pairs of rollers with horizontal axes, wherein the rollers of each pair are arranged laterally on opposite sides with respect to an imaginary vertical median plane, at which the stocking is fed to the turning machine by means of an appropriate gripper that places the stocking between the lower pair of rollers so that the toe of the stocking is just above said pair of rollers.
Above the rollers there is a rod or stem that is arranged so that its axis is vertical and lies in said median plane. The rollers can move on command towards or away from each other, so as to laterally engage on opposite sides the stocking that is arranged between them; furthermore, the rollers can be rotated about their respective axes, whereas the rod can move along its own axis so that it lies between the rollers of a same pair.
Said rollers are actuated for rotation about their respective axes by means of one or more constant-speed electric motors, whereas the mutual approach or spacing of the rollers is achieved by means of pneumatic cylinders; likewise, the movement of the rod along its own axis is also actuated by means of a pneumatic cylinder.
During the operation of these known types of machine, the gripper, while holding the linked or sewn stocking (which is inside-out) by its toe, places the stocking item between the lower rollers, which are in the mutually spaced position, so that the toe is located directly above said rollers. Then the lower rollers are moved mutually closer so as to retain the stocking between them and the gripper is disengaged from the toe of the stocking and moved away from the rollers. The lower rollers are then rotated about their respective axes in mutually opposite rotational directions, so that their peripheral speed at the region of contact with the stocking is directed upwards, i.e., towards the rod, which is actuated so as to engage the tip or toe of the stocking, which by virtue of the rotation of the lower rollers, begins to turn the right way out along the rod. The upper rollers are then moved into the mutual approach position and are rotated about their respective axes in a similar manner to the lower rollers, so that when the stocking arrives at the upper rollers while it is being turned the right way out along the rod, the stocking is also gripped by said rollers and is turned completely the right way out along the rod.
At this point, the direction of the rotation of the lower rollers is reversed; in this manner, the rollers remove the stocking and move it away from the rod, which is then returned to the starting position.
Said conventional machines for turning stockings the right way out, however, have some drawbacks.
During the operation for turning the stockings the right way out on the rod, slippage in fact occurs between the lower rollers and said stocking and can lead to damage to the stocking. Furthermore, since the mutual approach of the rollers is actuated by pneumatic cylinders, depending on the type of stocking to be turned the right way out and particularly on the thickness of the fabric of said stocking, it is necessary to perform adjustments of the pneumatic cylinders every time the type of stocking to be turned the right way out changes, and it is also necessary to manually adjust the stroke of the rod to adapt it to the length of the stocking to be turned the right way out to avoid damaging it or to allow to turn it the right way out.
The use of pneumatic actuators to actuate the various movements of the parts of the machine also requires the presence of a system for supplying compressed air as well as continuous manual adjustments of the pneumatic circuit to obviate drawbacks arising from accidental variations in operation that are typical of pneumatic components.